Why not bomb Bahrain? Why not declare a no-fly zone over Yemen? Such questions are aired increasingly on the internet – implying that in the light of all the popular uprisings in the Middle East and the authorities' attempts to suppress them, military intervention in Libya is a case of double standards.

It's true, of course, that Bahrain and Yemen are regarded as western allies whileMuammar Gaddafihas been an international pariah for most of his 43 years in power and few will be sorry to see him go. But that is not the only reason for treating Libya differently.

In principle, the question of who governs each country is a matter for its own citizens to sort out, and as far as possible they should be left to do so. This is especially important in the Arab countries that have a long history of political manipulation from outside: Arabs alternate between complaining about western intervention and demanding that the west steps in to solve their problems for them.

The result has been a long-standing dependency culture which – thankfully – Tunisians and Egyptians began to shake off when they overthrew their presidents. They accomplished their revolutions without significant foreign help and, in the long run, they will be all the better for that.

The problem, though, is that dictators don't give up power readily and in the process of getting rid of them people are liable to be killed. It happened in Tunisia and Egypt, and it's happening in Bahrain, Yemen and – to a much greater degree – in Libya.

So, while it's important to let people determine their own future, there's a conflicting pressure to get involved when lives and human rights are at stake.

In an effort to clarify the position, the UN's 2005 world summit established an international norm known as "responsiblity to protect" (set out herein paragraphs 138 and 139):

"Each individual State has the responsibility to protect its populations from genocide, war crimes, ethnic cleansing and crimes against humanity. This responsibility entails the prevention of such crimes, including their incitement, through appropriate and necessary means."

It goes on to say that the international community, through the UN, has a responsibility "to use appropriate diplomatic, humanitarian and other peaceful means ... to help protect populations from genocide, war crimes, ethnic cleansing and crimes against humanity". It also permits military action through the UN "should peaceful means be inadequate and national authorities manifestly fail to protect their population". (...)

(...)There is a further argument that Libya was a test case: if R2P was ignored on this occasion the whole principle of protecting civilian populations would have been seriously weakened, if not rendered totally worthless.

This is not to suggest that intervening in Libya was necessarily a good idea militarily or politically. AsJonathan Freedland says, the trouble with it is not "the abstract principle but the concrete practice". There will always be debates about the implementation and questions about whether the number of deaths would have been higher or lower if Libyans had been left to their own devices. Either way, though, it deserves to be recognised as an intervention based on principle and not as the "petro-imperialist" plot that Gaddafi claims it to be.

If anyone is to be accused of double standards, it should be the Arab League, which initially supported the no-fly zone, wavered when the bombing started, and now seems to have swung back in support of it.

At the same time, though, the league is supporting another kind of "responsibility to protect" – the protection of repressive regimes in the Gulf. Yesterday, while rejecting "any foreign interference", itendorsed the sending ofSaudi troopsto prop up Bahrain's beleaguered king.